From Lab to Revenue — The Deep Climate Tech Founder’s Journey with Jerome Gilleron 🚀

Greetings to 3k+ Impact Supporters! 🌍 It’s Jonas Ahm-Lundgren 👋 This week’s episode is a little different. Instead of hosting, I join Jerome Gilleron as a co-host/guest on the Reactor Podcast, and it turned into one of the most thoughtful conversations I have had in a long time about early-stage climate tech, founders, and the communities that support them.Jerome has built Reactor as a space where deep tech and climate converge, away from the hype cycles, clickbait, and AI-driven noise. We talk about ambition, feedback, storytelling, and the subtle art of moving fast without losing direction.Thanks for reading Impact Supporters! Subscribe for free to receive new posts and support our work.📋 What’s Inside🌱 Anchoring Purpose - Why climate communities can give founders clarity and momentum 🚀 From Pre-seed to Series A - Understanding the leap and why so many misjudge it 🧪 Proof of Customer - Why early demand beats technical proof 🎯 Pitching to Strangers - The underrated superpower for early founders 🧭 Feedback That Helps - Learning who to listen to and when 🌋 Ambition with Grounding - Thinking big while staying disciplined 🗣️ Human Storytelling - Why authenticity will always matter more than AI 👋 Meet Jerome GilleronWith a background in technology and entrepreneurship, Jerome Gilleron has spent years building and advising early-stage start-ups. He is the founder of Reactor, a climate-tech and deep-tech community connecting founders, investors, and experts to tackle the challenges of scaling impactful companies 🌍 Jerome is passionate about creating spaces that prioritize clarity, collaboration, and long-term impact in the fast-moving world of climate innovation.🌱 Why the climate community can give founders clarity and momentumJerome explained that Reactor became focused on climate and deep tech partly because the broader tech discourse kept drifting into hype cycles. Climate, by contrast, demands patience, precision and storytelling that respects complexity.He put it well:“You can’t cover climate like a trending topic. You need to treat it like a long-term craft.”For him, Reactor is more than a network. It is an anchor in a world where attention is scattered, and hype can drown out substance. Climate solutions need patience and nuance, and communities help create the conditions where both can thrive 🌿I have seen the same dynamic in Impact Supporters. People come here because they want to engage with ideas that matter. They bring curiosity, humility, and a desire to learn. That kind of shared intention creates clarity. It helps founders filter noise from signal and make decisions with more confidence.Jerome calls this “staying close to what matters.” For me, it captures the heart of what these communities do. They create a place where founders can think deliberately, ask better questions, and move forward with a steadier hand 🛠️🚀 Understanding the leap and why so many misjudge itA theme that comes up again and again is how often founders misjudge the leap between funding stages. At pre-seed, a working prototype feels like momentum. By seed, investors want early commercial traction. At Series A, they expect evidence of real market pull.Both Jerome and I have seen the same pattern. Founders sometimes get lost in technical validation without asking the harder question: does anyone actually want this? 🤔The teams that tend to scale understand something crucial. They think about demand from day one. They talk to potential customers. They test assumptions. They move quickly from theory to interaction. That shift in mindset often determines whether a company grows or stalls. 🧪 The underrated superpower for early foundersFor Jerome, proof of customer is far more powerful than proof of concept. Real engagement, interest, or willingness to pay tells a clearer story than any lab result or performance spec.I have watched this play out many times. Teams that embrace customer conversations early move faster. They make sharper decisions. They communicate their vision with confidence because they have felt the pull from the real world.Proof of concept is a promising beginning. Proof of customer is the momentum that carries a company forward 🚀🎯 The underrated superpower for early foundersJerome has a deceptively simple exercise he recommends to early founders: take your idea to strangers. Not to sell, but to listen.It is humbling. It is messy. And it tends to reveal things that nothing else will. People who owe you nothing give you pure, honest feedback. They surface confusion you didn’t see, highlight what resonates, and expose assumptions you didn’t realize you were making 📝Founders who lean into this discomfort learn faster. Their messaging sharpens. Their conviction grows. Most importantly: they discover the language that connects their product to the real world.🧭 Learning who to listen to and whenFeedback is everywhere. Investors, mentors, advisors, and even customers have opinions, and a founder trying to take every voice seriously quickly gets lost in noise.Jerome stresses the value of curating a small circle of trusted voices. A handful of people whose experience, honesty, and alignment matter. Once that circle is in place, the next step is action. Even with incomplete information, decisive execution aligned with your mission beats hesitation every time⚡It is the discipline of staying flexible while keeping your center of gravity.🌋 Thinking big while staying disciplinedAmbition alone is not enough. The founders who tend to succeed combine sharp vision with careful pacing. They hire thoughtfully. They scale deliberately. They stay focused on the handful of priorities that matter most 🎯This grounded ambition becomes a stabilizing force. It allows teams to adapt to uncertainty without losing momentum. It creates a culture where progress feels both steady and meaningful.Real impact is rarely explosive. More often, it is built through consistency, clarity, and disciplined execution.🗣️ Why authenticity will always matter more than AIEven in an era flooded with AI-generated content, storytelling remains profoundly human. Empathy, curiosity, lived experience — these are the qualities that shape narratives people care about 🤝In climate tech, storytelling becomes a bridge between complex problems and the people working to solve them. It helps teams communicate not only what they are building but why it matters.Communities like Reactor and Impact Supporters preserve that human layer. They create spaces where authenticity can flourish and where founders can speak with clarity rather than choreography.Thanks for reading Impact Supporters! This post is public so feel free to share it.✨ Closing ThoughtsOur conversation reminded me that building impact is rarely a straight line. It requires the discipline to stay close to what matters, the courage to ask difficult questions, and the humility to keep learning. It also demands ambition that is grounded in reality rather than hype 💡Clarity, curiosity, and human connection — these are the tools that help founders navigate uncertainty and move with intention.Thank you for being part of this community! Impact Supporters exists because of your engagement, your questions, and your willingness to think deeply about the future we are building together Who should we talk to next? What are the big, messy questions you are wrestling with? Hit reply or send us a note — I always love hearing from you.👋Thanks for listening and reading, Jonas This is a public episode. If you would like to discuss this with other subscribers or get access to bonus episodes, visit impactvc.substack.com